[DO NOT MERGE] Skip SystemUpdatePolicy Tests

They have a side effect of causing the device to be upgraded during
test, which is not desirable. Disable the tests for now until we figure
out another way to test.

Bug: 145932189
Test: atest DeviceOwnerTest#testSystemUpdatePolicy
Test: atest DeviceOwnerTest#testSystemUpdatePolicyLogged
Test: atest MixedDeviceOwnerHostSideTransferTest
Change-Id: I91d84d1418069a8242f75aeb4a6c4b0091d7bcd8
Merged-In: I91d84d1418069a8242f75aeb4a6c4b0091d7bcd8